The 1997 El Niño: Potential effects in New Jersey - September 1997 to April 1998

Climate Prediction Center (CPC), NWS/NOAA

Updated 2 December 1997

We are currently in the midst of a strong El Niño (warm) episode, which is forecast to continue
through February-April 1998. During this period the tropical ocean surface temperatures are forecast
to remain comparable in magnitude and areal extent to that of 1982-83, which is considered to be
the strongest warm episode of this century. In contrast to the 1982-83 El Niño, which caught the
country by surprise, the present El Niño was predicted several months in advance. This improvement
in climate prediction is the direct result of intensive research efforts by NOAA and its partners
during the last 15 years. Part of this research effort, which is still ongoing, has been devoted to
determining the effects of El Niño on temperature and precipitation patterns in the U. S. and
globally. Some results of this research for your state are discussed below.

The information on state impacts is derived by looking at what has happened in those years during
the past century that featured strong El Niño episodes. Four products are included for every period
for which effects are highlighted. El Niño impacts vary with season. The first contrasts average
conditions during El Nino episodes with what is expected in general. These figures for precipitation
also include what took place in 1982/83 as a plausible scenario as to what might happen, because the
present El Niño is at least as strong as any on record. These two estimates give a range of what might
be expected. However, because of the probabilistic nature of the forecasts, the range could be
greater. The second gives the change in probabilities for the respective variable and period. The
Climate Prediction Center of NOAA makes seasonal forecasts for temperature (precipitation)
probabilities in three categories: the warmest (wettest 1/3); the near normal 1/3; the coldest (driest)
1/3. The probability of getting any one of these three categories would be equally likely in the
absence of El Niño. Probabilities of being wetter or drier or warmer or colder than normal can be
dramatically changed by El Niño. The third and fourth products for each period are U.S.-wide maps
of respectively (1) average temperature or precipitation rankings during El Niño episodes and (2)
corresponding probabilities of the three categories. These maps place effects at the state level in a
broader context.

Historically, strong El Ninos have featured, on the average, dryer than normal conditions in the Fall
(September through November) and warmer than normal conditions in the pre-Winter (November
and December) in New Jersey. This scenario has more reliably occurred in the coastal plain and
piedmont portions of the state.